A signal sequence trap based on cell enrichment using Anti-CD19 antibody coated magnetic beads

Precursors of many secreted and cell surface proteins contain NH2-terminal signal sequences that lead proteins into the endoplasmic reticulum and to t he cell surface. Methods have been developed to clone and identify such pro teins by trapping their NH2-terminal signal sequences, so called signal seq uence traps. In this study we present an alternative and simplified signal sequence trap based on the combination of a novel vector construct expressi ng a cDNA library in fusion with a CD19 reporter gene, transfection in mamm alian cells and selection of cells expressing trapped signal sequences usin g magnetic beads. Using this method we have isolated several known and nove l factors with signal peptides.